Electric welding gun with a rotary torch head

ABSTRACT

Electric welding gun with a rotary torch head which with its auxiliary devices, is housed in an outer casing (1), on which a supporting casing (2) is constructed for handling the welding gun and into which are jointly introduced the supply lines for the torch head and the auxiliary devices. In the supply lines are provided liquid and gas lines issuing into ring chambers (43) axially sealed at either side and to which are connected line ducts (46) formed in the drive shaft (29), together with electrical lines connected to a current transfer mechanism for transferring the welding current to shaft (29). The current transfer mechanism is constructed as a contact brush (33) engaging on shaft (29) and the latter is made from a slip ring material. Each of the ring chambers (43) is axially constructed between retaining rings (44) arranged in pairs on a bush (47) fixed to shaft (29) and has holes (48) connecting the particular opening of the line ducts (46) in shaft (29) to the associated ring chamber (43). Each of the supply lines in the supporting casing (2) has a line coupling (3 to 7) constructed as a plug connection. The supporting casing (2) is subdivided into a plug box (8) and a socket box (9), whose assembly leads to all line couplings (3 to 7) being coupled together (FIG. 3).

The invention relates to an electric welding gun with a rotary torchhead.

In addition to a welding electrode positioned on the rotary torch headand connected to a welding lead, such welding guns generally have aninert gas nozzle connected to an inert gas line, a liquid cooling of thewelding head with a liquid feed line and a liquid return line, acontrollable drive motor for the welding head and frequently a fillerwire reel with a separate wire feed motor positioned on a reel holderrotatable with the driving shaft of the welding head about its rotaryaxis and supplied and controlled by corresponding control lines. Theinert gas, the cooling water, the welding current and other feed andcontrol currents for electrically driving auxiliary devices rotatablewith the torch head must therefore be transferred via correspondingdistributors from the fixed casing of the welding gun to the rotorcarrying the torch head and the auxiliary devices rotatable with it.

From DOS No. 2,723,034, it is known to transfer the welding current fromthe boss, made from electrically conductive material of the drivingshaft carrying the torch head to the latter by means of driving shaftball bearings running in a mercury bath. This is intended to provide aconstant, low current passage resistance, so that, even in the case ofhigh current intensities, the welding current level is kept constantduring welding. However, on the one hand the mercury bath increases theresistance to rolling of the ball bearings and on the other hand, inorder to protect both the environment and the worker, it is necessary totake expensive measures for sealing the areas containing the mercury andthe mercury line into the welding gun.

In addition, in the known welding guns, the distributor ring chambersfor the inert gas and cooling water are sealed by 0-rings arranged ininternal slots of the hub of the driving shaft of the torch head andrests in sliding manner on said shaft. However, for a good, permanentand wear-resistant sealing of the gas and liquid distributors of awelding gun, O-rings, which are mainly intended for sealing parts whichare not movable relative to one another, are disadvantageous, even ifthe speed of the torch head and its driving shaft is low. If, inaddition, the driving shaft is made from a relatively soft light metalalloy, running grooves form in the shaft due to friction on the pointsof the O-rings.

The supply lines for the torch head and its auxiliary devices arecombined into a welding cable and are jointly introduced into andremoved from the welding gun and in the gun casing are connected to theassociated supply distributors. If welding is carried out with thewelding gun, e.g. at a building site, the welding cable can be damagedby site traffic. In these cases, it is advantageous if the damagedwelding cable can be replaced as swiftly and rapidly as possible byanother welding cable. For this purpose, it is necessary to arrange thesupply line terminals and connections on the welding gun so as to giveoptimum easy access, thereby permitting rapid removal and replacement.It is also desirable to be able to simply and rapidly produce or detachthe supply line connections with respect to the welding gun in casessuch as e.g. the internal welding of a container, so that the weldinggun can be passed through the man hole into the container without thewelding cable, followed by connection to the latter in the container.

An object of the invention is to so construct an electric welding gunwith a rotary torch head that a good current transfer to the drivingshaft of the torch head, accompanied by a limited, constant transferresistance and a good sealing of the gas and liquid distributor fortransferring the cooling fluid and inert gas to the rotary torch headare ensured.

A further object of the invention is to so construct an electric weldinggun with a rotary torch head that it is easily and rapidly possible toproduce and remove the line connections between the gun and the weldingcable containing the supply line for the same.

According to the invention, an electric welding gun is provided with aspecial distributor assembly for transferring the cooling fluid, inertgas and electric current to the rotary torch head and to the auxiliarywelding devices. For the transfer of the fluid and gas, the associatedfluid and gas lines in each case issue into an annular chamber, which,according to the invention, are constructed between seal rings, whosesealing lips engage on the outer surface of a bush with a hard, groundsurface. Thus, a permanent, low-wear, good sealing of the annularchambers is obtained. Furthermore, according to the invention, thewelding current transfer to the welding head driving shaft takes placeby means of a contact brush and the welding shaft is made from a slipring material. This ensures a constant, permanent, low-loss currenttransfer of the welding current, even in the case of a high currentintensity. It is possible to choose a mating of materials for the brushand the driving shaft which furthers the sought objective of a goodcurrent transfer, without being restricted by the additional conditionthat the shaft material must simultaneously also be suitable forobtaining such a surface quality and hardness as is required for a goodsealing of the gas and fluid distributors. In the case of a copperbronze carbon brush, the driving shaft material is preferably analuminium alloy of the type AlMgSi 0.5F22. The bush is preferably madefrom steel.

As a result of the invention, it is also unnecessary to form costly andcomplicated internal slots in the driving shaft boss for forming theannular chambers, because in the present case the chambers are formedbetween the particular pairs of seal rings and the rings forming eachpair can be maintained with the appropriate spacing by means of drilledspacing rings.

In addition, the invention provides an electric welding gun with arotary torch head and with a special supply assembly for connecting thetorch head supply lines to the distributor for transferring the coolingfluid, inert gas and electric current to the rotary torch head.According to the invention, the supporting casing of the welding guninto which all the supply lines are introduced together, is subdividedinto a plug box and a socket box for forming a multi-point connector andto each of the said boxes is fixed one of the two coupling parts of theline couplings constructed in each case as a connector. Therefore, allthe line couplings can be formed by mounting the plug box into which thewelding cable is introduced, on the socket box on the welding guncasing, whilst they can be jointly removed by removing the plug box fromthe socket box. The plug box clearly offers a good possibility forsecuring the end of the welding cable for forming a reliable and durabletension relief on the plug box.

The aforementioned construction according to the invention also makes itpossible to couple the welding gun with different plug boxes, asrequired. Thus, in particular, one plug box can be constructed as a gunhandle to whose hollow portion can be introduced the welding cableenabling the gun to be operated as a hand gun by its handle, on whichare provided appropriate operating switches in such a way that they canbe easily operated. The other plug box can be fitted to a manipulator,so that for operation by the manipulator, the welding gun only has to bemounted by the socket box of its support casing on the plug box of themanipulator to fix it to the latter and simultaneously obtain the linecouplings.

The invention is described in greater detail hereinafter relative tonon-limitative embodiments and the drawings, wherein show:

FIG. 1 a side view of a welding gun in diagrammatic form.

FIG. 2 the front view of the supporting casing of the welding gun ofFIG. 1 along line A-A therein.

FIG. 3 the longitudinal section through the supporting casing of FIG. 2along intersection line B-B therein.

FIGS. 4 to 6 details of a contact brush for welding current transfer tothe rotary welding head.

FIGS. 7 to 9 details of a control line distributor for the controlcurrent transfer to separately driven and controlled auxiliary devicesrotatable with the rotary welding head.

Only an external view of the welding gun is provided in FIG. 1. The gunhas an outer casing 1 in the form of a tubular protective casing 24 anda base casing 25 extending from the bottom of the former. The rotarytorch head (not shown) is placed in protective casing 24 on theleft-hand side in FIG. 1 and is driven by a shaft extending over thelength of said casing and is constructed in the rear part of the gun asa not shown reel holder rotating with the torch head and on which isarranged a filler wire reel together with its wire feed means. Theelongated base casing 25 contains at the rear end of the welding gun thedrive motor for the torch head and together with the front part forms asupporting casing 2 which in the lower part is constructed as a gunhandle with a hollow handle portion 19 through which is introduced intothe gun welding cable 23 containing the supply lines for the weldinghead and its auxiliary devices. A control switch 20 for controlling thewelding cycle is arranged at the front on the gun handle. An emergencyswitch 21 is positioned laterally on the gun handle and can be used forstopping the gun in emergencies.

For forming a multiple line coupling for all the supply lines containedin welding cable 23, supporting casing 2 is subdivided into a socket box9 at the front end of base casing 25 and a plug box 8 on which is formedthe handle portion 19 of the gun handle. By means of in each case onelocking device 10 at the front and rear ends of plug box 8 the lattercan be fixed to socket box 9. The end of welding cable 23 is fixed intension-relieved manner in hollow handle portion 19.

Supporting casing 2 (FIG. 3) contains a line coupling 3 to 7 constructedas a connector for each of the supply lines contained in the weldingcable. All the line couplings 3 to 7 are gently arranged in the verticalmedian longitudinal plane of supporting casing 2 and are alignedparallel to one another. One coupling part of each of the line couplings3 to 7 is fixed to one cover plate 27 of plug box 8, whilst theassociated other coupling part of line couplings 3 to 7 is fixed incorresponding arrangement and alignment in socket box 9, so that byfitting plug box 8 to socket box 9 all the line couplings 3 to 7 can bejointly and simultaneously coupled in.

The front part of supporting casing 2, to the right in FIG. 3, containsa group of three identically constructed line couplings 3 to 5 for theinert gas line, the cooling water feed line and the cooling water returnline. Each of these line couplings 3 to 5 has a cylindrical pipe nipple12 screwed to cover plate 27 of plug box 8 and projecting above the topof said plate 27. The nipple is peripherally provided with two slots forreceiving sealing rings 13 and a coupling sleeve 11 screwed in socketbox 9 in a through hole in an insulating tube 28 in which is mounted thetorch head shaft 29 by means of two ball bearings 30. The pipe nipples12 terminate in hose nipples 31 projecting beyond the bottom of coverplate 27 of plug box 8 and onto which is placed the particular line endof the gas or fluid lines and can optionally be secured by means of aclip or clamp.

The line coupling 6 for the welding current line 26 is connected to thegroup of three line couplings 3 to 5 for the gas or fluid lines. Onecoupling part of line coupling 6 is a longitudinally slotted conicalbush 15 fixed in an insulating casing in cover plate 27 and projectingover the top of the latter. Bush 15 is located in an insulating holder32 of a contact brush 33 screwed to insulating tube 28 within socket box9 and from the said brush the welding current is transferred to therotating shaft 29 of the welding head. As a result of the longitudinalslots in the hollow conical bush 15 the latter can resiliently expandsomewhat under the contact pressure by which it is pressed onto theconical mandrel 14 leading to a maximum contact surface between conicalbush 15 and conical mandrel 14 of the welding current line coupling 6.These contact surfaces are gold plated to give an optimum favourablecurrent transfer.

To the back of the welding current line coupling 6 is connected the linecoupling 7 for the control line, which as a multi-point connectorcomprises a socket 34 fixed to the base plate of socket box 9 and a plug35 fixed to cover plate 27 of plug box 8. The outputs of socket 34 areconnected via not shown line portions on the one hand to a controldistributor group 37 for the transfer of the drive and control currentsto the not shown filler wire feed drive rotating with shaft 29 and onthe other hand via corresponding connecting lines to the drive andcontrol inputs of the torch head drive motor located at the rear end ofthe welding gun. In addition, not shown branch lines are connected tothe outputs of socket 34 and lead to a reference socket 22 (FIG. 1)positioned in the rear part of the welding gun on the side of the basecasing 25 of the outer casing 1 thereof, so that at this point there isadditional access to the welding head control lines by means of a notshown control cable plug which can be plugged into the reference socket22.

With the exception of the welding current line coupling 6, all the linecouplings 3 and 5 and 7 are constructed in such a way that in theplugging direction the coupling parts engage in one another with aclearance, so that they do not represent limiting stops for the weldingcurrent line coupling 6, whose coupling parts 15, 16 can consequently bepressed against one another in the plug direction with the necessarycontact pressure, without it being a question of maintaining closepositioning tolerances for the parts of the other line couplings 3 to 5and 7. At least one of the two couplings parts 14, 15 of the weldingcurrent line coupling 6 can by adjustment undergo a position change inthe plugging direction e.g. by using a washer 38 of correspondinglychosen thickness for mandrel 14 which is screwed onto a screw bolt 39anchored in brush holder 32. It is also possible to in particularresiliently support the conical mandrel 14 in the plugging direction ifthe inherent resilience resulting from the construction of thelongitudinal slots in conical bush 15 is not sufficient for thispurpose.

In addition, the contact pressure for the welding current line couplinguntil cover plate 27 of plug box 8 strikes against base plate 36 ofsocket box 9 is determined by the locking device 10 for locking plug box8 to socket box 9. At the front and rear faces of supporting casing 2,locking device 10 has in each case a swing bolt 16, pivotable on socketbox 9 in an associated outer slot 17 which on the associated outside ofthe plug box runs in the swivel plane of swing bolt 16 parallel to theplugging direction of line couplings 3 to 7. The swing bolt can bebraced by means of a manually operable nut 18 engaging on the front edgeof the end of outer slot 17 on the plug box for the purpose of pressingthe latter against the socket box. In the socket box 9 the swing bolts16 have in each case a square head 40 which through a guidance slot 41,permitting the pivoting of square head 40, but preventing it fromrotating about the screw axis, projects beyond the base plate 36 ofsocket box 9 and there has a cross pin 42 pivotably resting on baseplate 36 on either side of guidance slot 41.

The coupling sleeve 11 of line couplings 3 to 5 for the inert gas and/orcooling water in each case issue with their end screwed into insulatingtube 28 into a distributor ring chamber 43, which is in open connectionwith an associated line duct 46 leading to the torch head andconstructed in the wall of hollow shaft 29. Ring chambers 43 are in eachcase constructed between two seal rings 44 facing one another by theirradially projecting inner sealing lips and with their outer peripheryengaging on the inner periphery of insulating tube 28 on which issupported shaft 29 by means of ball bearings 30. Between the seal rings44 associated with the same ring chambers 43, a cross-sectionallyU-shaped spacing ring 45 is introduced in each case into insulating tube28, so that it defines an external peripheral slot into which issues themouth of the associated coupling sleeve 11 and which is preferablymultiply drilled on its U-web, so that the necessary flow connectionwith the corresponding ring chamber 43 is formed. Adjacent seal rings 44of adjacent ring chambers 43 are supported with respect to one anotherby their axial backs. Seal rings 44 engage by their radially innersealing lips in sliding manner on a seal bush 47, which is mounted onshaft 29 and is fixed to shaft 29 on O-rings 49 secured between bush 47and shaft 29, so that they rotate with the latter. Between the sealrings 44 between each ring chamber 43, steel bush 47 has a row of radialconnecting holes 48 distributed over the bush circumference, whilstunder each circumferential row of connecting holes 48 a distributor ringslot 50 is formed in the outer circumference of shaft 29 and into whosebottom issues the associated line duct 46. Due to the fact that the ringchambers 43 are connected with the associated distributor ring slot 50via a plurality of connecting holes 48, there is a corresponding lowflow resistance for the flow medium to be introduced into the associatedline duct 46 in shaft 29 or for the cooling water return line for thewater flowing out of the associated line duct 46. In either side of eachdistributor wall slot 50, one of the O-rings 49 is positioned in a ringnut 51 formed in shaft 29, so that slots 50 are sealed on either side.

The welding electrode current is supplied to the torch head by shaft 29.The welding current is transferred to shaft 29 from brush 33 of weldingcurrent line coupling 36. Thus, shaft 29 is made from a slip ringmaterial, preferably an aluminium alloy which is adapted to the materialof brush 33, so as to ensure an optimum good, large-area currenttransfer after the reciprocal grinding of the contact surface of brush33 and the associated bearing surface of shaft 29. In the case of suchmaterial for shaft 29 it is rather complicated to ensure an adequatesurface quality in order to directly seal on the circumferential surfaceof the rotating shaft by means of seal rings the gas and fluiddistributors cooperating with the line ducts 46 in shaft 29 and therebyobtain an adequately good seal. Thus, in the represented embodiment, thesteel bush 51 is mounted on shaft 29. The ground outer surface of thesteel bush 51 rotating with the shaft with respect to seal ring 44ensures a good, weararm sealing of the gas and fluid distributors inconjunction with the sealing lips of the seal rings during the rotarymovement of shaft 29, whilst on the inside of steel bush 51 O-rings canbe provided for sealing purposes, because here there is no relativemovement between the parts to be sealed.

The construction and arrangement of contact brush 33 and its insulatingholder 32 on which is supported the conical mandrel 14 of weldingcurrent line coupling 6 is apparent from FIGS. 4 to 6. FIG. 4 shows thelongitudinal section containing the axis of shaft 29 corresponding tointersection line C-C in FIG. 5 in which the plan view is shown, whilstFIG. 6 shows the front view viewed parallel to the axis of shaft 29.Contact brush 33 is subdivided into two brush halves 52 arranged insuccession in the circumferential direction of shaft 29. These contacthalves 52 are separately slidingly guided in insulating holder 32 ofbrush 33 engaged in an opening of insulating tube 28 and screwed to thelatter and are pressed against the circumferential surface of shaft 29by a spring 54 supported on insulating holder 32. One end of a lineportion 53 in the form of a coil is soldered into each brush half 52. Attheir other end, the line portions 53 have in each case a circular diskmounted on the screw bolt 39 holding the conical mandrel 14 of thewelding current line coupling and secured to insulating holder 32 bymeans of a nut screwed to bolt 39 between mandrel 14 and holder 32.

As can be gathered from FIG. 3, brush 33 is located between the gas andfluid distributor group and control distributor groups 37 and has aplurality of slip rings 56 on an insulating bush 55 placed thereon innon-rotary manner with shaft 29. An insulating material holder 58 isengaged in a circumferential opening 57 of insulating tube 28 and isscrewed to said tube 28. Holder 58 carries a number of sliding contactsprings 59 corresponding to the number of slip rings 56 and said springsare connected to corresponding output of socket 34 of coupling 7 for thecontrol lines. In turn, slip rings 56 are connected by not shown lineconnections to the feed and control terminals of a filler wire feedmotor (not shown) positioned on a filler wire reel holder (not shown)flanged by means of flange 60 to the rear end of shaft 29 and by meansof which the latter is driven. The details of the control distributorgroup 37 can be gathered from FIGS. 7 to 9.

We claim:
 1. An electric welding gun comprising: a rotary driving shaftin an outer casing provided with a supporting casing for handling thewelding gun; a plurality of supply lines jointly introduced into thesupporting casing, said plurality of supply lines comprising liquid andgas lines including a cooling water feed line, a cooling water returnline and an inert gas feed line; means for conducting the output of eachsupply line into a respective axially sealed ring chamber in the outercasing for supplying line ducts formed in the rotary driving shaft, saidplurality of supply lines further comprising a welding current lineconnected to a current transfer means for transferring welding currentto the shaft made of electrically conductive material and electricalcontrol lines, each of said supply lines having a line coupling withinsaid supporting casing wherein each of said line couplings is a plugconnection and said supporting casing is subdivided into a plug box anda socket box adapted to be assembled to form the supporting casing andto be locked together in the assembled arrangement by a lockingmechanism, said plug connections extending parallel to each other andeach of said plug connections comprising two coupling parts, one fixedto said plug box and the other fixed to said socket box, whereby thesaid plug box and socket box cooperate to form a multi-point connectorin such a way that said two coupling parts of each of said plugconnections are commonly assembled by said assembling of the plug boxand the socket box.
 2. An electric welding gun according to claim 1,wherein said current transfer means is a contact brush engaging on thedriving shaft, said electrically conductive material of the drivingshaft being a slip ring material, and wherein the ring chambers are ineach case axially defined between seal rings arranged in pairs on a bushand provided with sealing lips which in each case face the associatedring chamber, said bush being fixed to the driving shaft and havingholes connecting the line ducts in the driving shaft with the associatedring chamber.
 3. An electric welding gun according to claim 1, furtherincluding O-rings arranged in ring slots of the driving shaft betweenthe driving shaft and said bush, in each case on either side of theassociated ring chambers.
 4. An electric welding gun according to claim1 wherein said bush has a row of connecting holes for each ring chamberdistributed around the bush circumference and said driving shaft undereach of said rows of connecting holes has a distributor ring groove intowhich issues a particular of said line ducts.
 5. An electric welding gunaccording to claim 1 wherein the contact brush is positioned betweensaid bush and a control distributor group having an insulating bushfixed to the driving shaft and provided with a plurality of slip ringscooperating with sliding contact springs fixed to the casing, saidelectrical control lines being connected to said sliding contactsprings.
 6. An electric welding gun according to claim 1, wherein saidline couplings of said liquid and gas lines are constructed as sealingcouplings in which one coupling part is constructed as a cylindricalsleeve and the other coupling part as a cylindrical pipe nipple whichcan be inserted into the sleeve and comprises at least one sealing ring,wherein further the line coupling for the welding current line is aconical coupling in which the one coupling part is a conical mandrel andthe other coupling part is a longitudinally slotted conical bush, andwherein the line coupling of the control lines is a multi-pin connector.7. An electric welding gun according to claim 1, wherein said lockingmechanism of said plug box and socket box comprises pivotably supportedswing bolts adapted to be swung into an outer slot of said plug box,said outer slot extending parallel to said plug connections, said swingbolts being further adapted to be braced to the plug box by means ofmanually operatable nuts.
 8. An electric welding gun according to claim1, wherein the plug box is constructed as a gun handle through whosehollow handle portion are passed the supply lines combined into a cableand which comprises a control switch and an emergency switch.
 9. Anelectric welding gun according to claim 6 wherein said line coupling ofthe control lines forms a branching connection leading to a referencesocket on the outer casing, the reference socket being spaced from thesupporting casing.
 10. Electric welding gun apparatus comprising:aplurality of supply lines for said gun; a rotary torch head drive shaft;a supporting casing for said rotary drive shaft subdivided into a plugbox and a socket box adapted to be assembled to form the supportingcasing and to be locked together in assembled arrangement by a lockingmechanism; a plurality of plug connections for said supply lines, eachcomprising two coupling parts, one being fixed to said plug box and theother being fixed to said socket box, whereby the said plug box andsocket box cooperate to form a multi-point connector in such a way thatsaid two coupling parts of each said plug connection are commonlyassembled by the assembling of the plug box and the socket box.
 11. Theapparatus of claim 10 wherein said drive shaft is formed of slip ringmaterial and further including:a plurality of line ducts in said driveshaft; means for communicating electric current to said drive shaft;bush means attached to said drive shaft, said bush means having aplurality of holes therein, each said hole connecting to one of saidline ducts; a plurality of ring chambers, each said chamber beingpositioned to communicate with a corresponding said hole; and aplurality of sealing rings arranged on said bush, each said sealing ringhaving a sealing lip which faces an associated ring chamber.
 12. In anelectric welding gun, the improvement comprising:a drive shaft having aplurality of line ducts therein; bush means attached to said driveshaft, said bush means having a plurality of holes therein, each saidhole connecting to one of said line ducts; a plurality of ring chambers,each said chamber being positioned to communicate with a correspondingsaid hole; and a plurality of sealing rings arranged adjacent said bushmeans, each said sealing ring having a sealing lip which faces a saidring chamber.
 13. The improvement of claim 12 wherein said drive shaftis constructed of slip ring material and further including a contactbrush means for communicating electric current to said drive shaft. 14.The improvement of claim 12 further including spacing ring means forminga fluid conducting path into each said ring chamber.
 15. The improvementof claim 14 wherein each of said sealing rings further includes asealing portion which abuts a respective spacing ring means.
 16. Theimprovement of claim 14 wherein each said sealing ring is of U-shapedcross-section having a first sealing lip abutting said bush and a saidring chamber and second sealing lip abutting a said spacing ring means.17. The improvement of claim 16 further including O-ring seal meanslocated between said bush means and said drive shaft.